Thermally controlled switch



Sept.-3, 1935. J. F. FRESE 2,013,628

THERIALLY CONTROLLED SWITCH Filed Sept. 26, 1954 Patented Sept. 3, 19352,013,628

UNITED STATES PATENT OFFICE THEBMALLY CONTROLLED SWITCH Joseph F. Frese,Baltimore, Md., assignor to Monitor Controller Company, Baltimore, Md.,a corporation of Maryland Application September 26, 1934, Serial No.745,625

12 Claims. (01. 200-122) This invention relates to a thermally operatedconstruction of both elements will be understood circuit controllingdevice and particularly to from a description of element l2, whichcomcompensating thermally responsive elements prises a tube formed iroma helically coiled flat which will operate the controlling device thebi-metallic strip it. The lower end of the tube.

I same under identical operating conditions irrewhich is preferablyarranged vertically by suitspective of changes in atmospherictemperatures. able mounting of the base, is open and secured The type ofthermally responsive element to as by soldering or brazing within anopening in which the present invention relates generally is the lowerbracket arm I6 01! a strap ll secured that shown in the patent grantedMay 10, 1927, to the base behind the tube. This fixes the lower 10 toGeorge H. Whittingham, No. 1,627,816 for end of the tube rigid. "Theupper end is closed 10 Thermal limit relay, comprising a tubular housbya permanently attached hub is from which ing composed of aflat-bimetallic strip wound extends an arm ll carrying the insulatingbutinto the form of a helix arranged vertically with ton IQ foroperating the switch tripping mechaits lower end open and secured to asuitable supnism. This hub is iournaled on a stationary pin port and itsupper end closed and tree to turn. mounted in the upper flange 2i of thestrap 15 A heating element, comprising a part of a cirll which guidesthe upper end of the tube but cult, the flow of current in which isadapted to permits it to rotate by the coiling or uncoiling of controlthe switch of the device, is inserted into the strip from which it isformed. the housing through its lower end, and the heat The heatingelement consisting of a wire 22 no generated by the current in theheating eledoubled upon itseli and having its ends secured 20 mentcauses the housing to partially uncoil to to binding posts 23 and 24, ispassed through the operate the switch. Such a thermally responaperturein bracket it into the interior of the sive element is caused tooperate, more or less, tube l2. The binding posts may be included in aby the temperature of the surrounding air and circuit, the current ofwhich operates the circuit as in order to compensate for changestherein, the breaker. 25 present invention contemplates interposing aThe element ii is identical in construction with second thermallyresponsive element between the the element i2 except that it isoppositely wound current heated one and the switch which eleso that itsbutton it is adapted to be moved in ment is subject to only the airtemperature, and the same direction as the button it when its no changesin response thereto in an opposite sense heating element, which may bein the same or a to the first element. diflerent circuit from the one inelement I2, is

For a full understanding of the invention, refenergized. The buttonsoperated by the thererence may be had to accompanying drawing and mallyresponsive elements are located under furand following specification,wherein is disclosed cations 25 on the end of a tripping lever a.

88 a single exemplary embodiment of the invention The tripping lever ahas integral ears II at its with the understanding that such changes mayopposite edges which are pivoted to ears 28 exbe made therein as fallwithin the scope of the tending from a strap 29 secured to the base ill.appended claims without departing from the A light spring ll between thelower end of the spirit of the invention. tripping lever and the strap29 presses the bi- 4. In said drawing; furcated upper end of the levertoward the but- Fig. l is a front elevation oi an apparatus contonsl9-it'.

structed according to the present invention; Any suitable form of switchmechanism may Fig. 2 is a right side elevation of the same; be operatedby the tripping lever or directly by the Fig. 3 is a central verticalsection of the device thermal elements either in the arrangement d8 ofFig. 1; and, shown or in other suitable arrangements. The

Fig. 4 is a transverse section taken on line preferred switch mechanismcomprises a station- 4-4 of Fig. l. ary contact member 3i supported fromthe base In the drawing, it represents a base of suitable it and aspring contact arm 32 which is secured insulating material and II and I!are thermalto a cross-piece 33 on a resetting lever c. This lyresponsive elements, each adapted to operate lever comprises a sheetmetal cross-piece 35 hava circuit breaker or switch it. These elementsing a handle 36 secured to its central portion and are alike except thatbeing arranged on oppohaving at its ends two parallel arms 31 which aresite sides of the circuit breaking switch, they pivoted to ears 3!projecting outwardly from the are constructed so as to twist in oppositedirecplate 2!. The cross-piece 33 is secured to the I tions when heatedto operate the switch. The lower edges of the arms 31 and a portionoi'the spring contact member 32 is bent into il--forzn at 32 and fitsaround the inner edge or" said cross-piece, where it is secured. Thelower end 32" of the spring member is turned downwardly near the outeredge of the cross-piece 33 to form a stop for an extension of thetripping lever now about to be described.

A bi-metallic strip 12 is bent into substantially loop form and has itsshorter leg 43 secured as by riveting to the upper face of the trippinglever a. The longer leg 44 extends back over this short leg and is bentinwardly as at 45 and then up wardly to provide an end i8 which engagesunder the lower face of the cross-piece 33 of the resetting lever of theswitch to restrain it in circuit closing position, as shown in Figs. 2and 3. Under these conditions the under-surface of the end of this bimetallic strip rests on the stop 32".

Under the conditions just described, if either of the thermallyresponsive elements it or 12 is sufficiently heated by the passage ofcurrent through its heating coil, it uncoils and one of the buttonsl9-l9 engages under a limb of the tripping lever and rotates it in a cotdirection as viewed in Figs. 2 and end 46 from beneath the crossbar 33and into position below the opening 42 between this and the crossbar 35so that the switch now drops open by gravity to the limit permitted bythe stop lugs 48 formed integrally witn the switch frame and whichengage the plate 29.

bi-rnetallic strip 1; attached to the tripmetals so selected and dis end46 held stationary by crossbar 33 and stop 535i", 1 of change of shape,due to variations the temper .ture of the surrounding air, is

ng lever r the same rate and direction as the surrounding airtemperature causes the the with the so that clearance 51} between theseparts mains substantially constant. is insures that the switch will betripped under same oper ating conditions at all temperat' s. of the surrounding air so that the same tr elem nt of operation will exist foreach. opera co The interposed thermal element 2; either of the operatingelements 5 is not subject to their heating freely exposed to theatmosphere so b pensating changes taire place with tl ity as do changesin the thermal elelr I2 resulting from air temperatures.

What I claim is:

i. In a circuit controlling device, in CC'HiiJi" tion, switch comprisinga stationary n and a movable member, a th rmally resp element adapted toactuate the movable me to operate the switch, a heater said element, anda bimetallic loop interposed between said element and movable member,said loop being spaced laterally from said element and heater so as tobe subject only to atmospheric temperatures.

2. Ina circuit controlling device, in comhina" tion, a switch comprisinga stationary member and a movable member, a lever, a bimetallic loopmovable member, a thermally responsive element adapted to actuate saidlever when heated move the same and to thus move said loop, and heaterfor said element adapted to be connected into a control circuit.

3. a circuit controlling device, in tion, a switch comprising astationary contact,

movable member carrying a second contact for engagement with anddisengagement from the first, means to maintain the second member out ofnormal position and including a tripping lever and a bimetallicextension thereon engagcable with said member, a thermally responsiveelement adapted to actuate the tripping lever to disengage the extensionfrom the member to com dition it for return to normal position, and aheater for said element.

4. In a circuit controlling device, in combination, a switch comprisinga stationary contact, a movable member carrying a second contact forengagement with and disengagement from the first, means to maintain thesecond member out of normal position and including a tripping 1everhaving an operating button, a bimetallic extension on said leverengageable with said member, changes in atmospheric temperature causingchanges in shape of said extension to move said lever and button, athermally responsive element having an arm spaced from said button, anda heater for said element to cause it to distort and press the armagainst the button to release the extension from the member to trip theswitch.

5. In a circuit controlling device, in combinaswitch comprising astationary contact, a movable member carrying a second contact forengagement with and disengagement from the first, means to maintain thesecond member out of normal position and including a tripping leverhaving an operating button, a bimetallic extension on said leverengageable with said member, changes in atmospheric temperature causingchanges in shape of said extension to move said lever and button, and aheater for said element to cause it to distort and press the arm againstthe button to release the extension from the znemoer to trip the switch,said bimetallic extension and said thennally responsive element beingcoordinated to maintain a substantially uniform spacing between saidbutton and arm with changes in atmospheric temperature.

6. In a circuit controlling device, in combination, a switch comprisinga stationary and a mov able member, said movable member having normaland restrained positions, an elongated bimetallic strip having one endadapted to hold said member in its restrained position, athermalrceponsive element, an electric heater thereor adapted to causemovement of a part of said lenient energized, and means associating partand opposite end or said strip where strip is moved to release themember when the said element is heated.

i. In circuit controlling device, in combination, switch comprising astationary and a movsaid movable having norstrained positions, anelongated biretallic strip having one end adapted to hold member in itsrestrained position, a thermalsponsive element, an electric heater thereadapted to cause movement of a part of said element when energized, andmeans associating said part and the opposite end of said strip eby thestrip is moved to release the mem- -en the said element is heated, saidbimetalstrip being constructed to compensate for -oveinent of the the].rally responsive element part under the action or atmospherictemperature -anges, wl'iereby actuation of the switch by the heatingelement is the same at all times for the same condition of heating.

8. a circuit controlling device, in combination, a switch comprising astationary and a movable contact, a resetting lever for said movablecontact normally holding it separated from the stationary contact, apivoted tripping lever, a thermally responsive element having a partmovable to actuate said tripping lever, an electric heater for saidelement to cause it to move said pen, a bimetallic strip extending fromsaid tripping lever into the path or said resetting lever and adapted tohold the same in switch-closing position when manually set, movement 0!said thermally responsive element part serving to move said strip totrip the resetting lever, said strip being constructed to compensate formovements oi said part responsive to changes in atmospheric temperature.

9. In a circuit controlling device, in combination, a switch comprisinga stationary and a movable contact, a resetting lever for said movablecontact normally holding it separated from the stationary contact, apivoted tripping lever, a thermally responsive element having a partnormally spaced from and movable to actuate said tripping lever, anelectric heater for said element to cause it to move said part to closesaid space and move said lever, a bimetallic strip extending from saidtripping lever into the path of said resetting lever and adapted to holdthe same in switch closing position when manually set, movement oi saidthermally responsive element part serving to move said strip to trip theresetting lever, said strip being constructed to compensate formovements of said part responsive to changes in atmospheric temperatureto maintain said space substantially constant.

10. In a circuit controlling device, in combination, a suitable base, astationary contact thereon, a resetting lever pivoted to said base, acontact on said lever out of engagement with the first contact when thelever is in its normal position and engaging the first contact when thelever is in a restrained position, a pivoted tripping lever, a thermallyresponsive coil having a part normally spaced from said tripping lever,an electric heater for said coil to cause it to move said part to closesaid space and move the tripping lever with its free end in the path ofsaid resetting lever, said end being adapted to hold the resetting leverin restrained position when the same is manually set, movement of theresetting lever serving to move said strip end to trip the resettinglever, said strip being constructed to compensate for movements of saidpart responsive to changes in atmospheric temperature by moving thetripping lever to maintain said spacing substantially constant.

11. In a circuit controlling device, in combination, a suitable base, astationary contact thereon, a resetting lever pivoted to said base, acontact on said lever out of engagement with the first contact when thelever is in its normal position and engaging the first contact when thelever is in a restrained position, a pivoted tripping lever, a thermallyresponsive coil having a part normally spaced from said tripping lever,an electric heater for said coil to cause it to move said part to closesaid space and move the tripping lever, a long bimetallic stripextending from said tripping lever with its free end in the path of saidresetting lever, said end being adapted to hold the resetting lever inrestrained position when the same is manually'set, movement 0! theresetting lever serving to move said strip end to trip the resettinglever, said strip being constructed to compensate for movements of saidpart responsive to changes in atmospheric temperature by moving thetripping lever to maintain said spacing substantially constant, and aspring to bias said strip end into resetting lever restraining position.

12. A thermally controlled switch mechanism comprising a helix composedof a bi-metallic strip, fixed at one end and having its opposite endfree to turn, an arm secured to and projecting laterally from the latterend, a lever having one end in position to be engaged by said arm, aspring normally biasing said lever toward the arm, a switch part,forming a stop, a bi-metallic loop having one leg thereof secured to thelever and having the free end of its other leg adapted to rest againstsaid stop in the closedposition or the switch, and a heater for saidhelix.

JOSEPH P. FRESE.

